Tracking water level fluctuations is important to the study and management of waterbodies. A geographic object-based image analysis using very high spatial and temporal radar interferometry (Cosmo-Skymed and TerraSAR-X) and optical (Pléiades) imagery is adopted in this study for this purpose. A linear regression model was sufficient to correlate the water surface area of a mildly sloping and unencumbered littoral zone spatial subset (extracted from 14 images) to water surface altitude data from the field. Results are excellent (R² = 0.963 and RMSE = 0.42 m for the unsupervised classification) albeit limited by the need for field data and the presence of a mildly sloping and unencumbered littoral zone.